The successor to the well known ETA 2824,
the ETA caliber 2892 is one of the smoothest winding, robust, stable timekeeping and thinnest mass produced movements on the market. It's no wonder that brands such as Omega, Rolex (via Tudor), Ball, Bell & Ross, Tag Heuer, and many more have used this movement (often under their own caliber designation) with great success. It's a stable timekeeper, and stable in all its positions. Watch movements are timed in different positions, as gravity and friction affects the isochronism of a watch, vertical positions will vary from horizontal as pivots will ride on their sides. The 2892 is very stable in all these positions, resulting in greater accuracy than its sister movement, the 2824.
The 2892 clocks in at just about 3mm (!) making it very thin, thinner than movements other common movements such at Seiko NH35 (almost 5mm), Miyota 9015 (known for being thin-ish), and of course the 2824. Many brands use this movement in dress watches, so they capitalize on the thinness there. Not too many brands capitalize on that sexy 3mm in other models, one of the Omega Seamaster has an Omega branded 2892, though it remains a rather average thickness for a diver.
The Calamity makes use of the 3mm thickness of the 2892 as well as some design tricks with the case to achieve the thinness that it has-in conjuncture with the water resistance (the real challenge is thinness AND water resistance, one without the other is easy). There was a period when the "Orion Dive Watch" was based on the NH35, it was thick and chunky, a bloated version of what we ended up on and I said, "I've had it with big chunky dive watches." and that design was scrapped and we started over. It's easy to make a thick dive watch, it's easy to fall into obscurity with a marine-themed name for your chunky dive watch; what's not easy is making a dive watch the most comfortable watch in your collection and come head to head in thickness with dress watches. And that's why the Calamity called for the ETA 2892.
A couple questions I get asked a lot are, "Why didn't you use the 2824/NH35/9015?". The NH35, while being an affordable workhorse is too thick to achieve this design feat with, so it was off the table. The 9015, recently inflated due to demand from other microbrands now rivals the 2824 in price, in my mind, it's not demanding of its inflated price. Then the good old 2824, standing a little thinner than the NH35 and a little better in terms of timekeeping, but much more expensive, it doesn't really let me accomplish the goal either. The 2892 dominates each of these movements in every category, reliability, stability, timekeeping, SMOOTH WINDING (the 2892 is INCREDIBLY smooth to wind, an essential and added perk when combined with the large Orion crown), and of course, thickness. It's simply the best choice of the competitors in the pool (ha), the only downside is the cost. The result, however, is a watch that can knock around with some of the big boys in its price bracket. I can guarantee it already beats them in thickness/WR combo and comfort, EASILY.